1. Field of the Invention
The present invention relates to a glass run for attachment along a doorframe of a motor vehicle.
2. Description of Related Art
As shown in FIG. 1, a glass run 10 is continuously attached along an inner periphery of a doorframe 12 of a door 14 of a motor vehicle. As shown in FIG. 2, the glass run 10 includes a main body 18 having a generally U-shaped cross-section, and seal lips 20 and 22 extending inwardly from ends of facing side walls 24 and 26 of the main body 18. The glass run 10 thus arranged is fitted into a channel 28 formed inside the doorframe 12 such that the seal lips 20 and 22 contact the peripheral portion of the door glass 16 from both sides thereof. The glass run 10 is generally composed of rubber and, more specifically, ethylene propylene diene terpolymer rubber (EPDM rubber). Recently, thermoplastic olefin elastomer (TPO) has been also used as the material for the glass run 10.
Just after the door 14 is closed hard with the door glass 16 half opened, or when the motor vehicle runs on rough roads with the door glass 16 half opened, noises occur in the glass run 10. These noises are caused by the seal lips 20 and 22 repeatedly striking on facing side walls 24 and 26 with the vibration of the door glass 16.
Conventionally, it has been considered that these noises are mainly caused by the seal lips 20 and 22 being pushed by the door glass 16 to rub inside surfaces of the side walls 24 and 26. And, based on this consideration, films of a material exhibiting high lubricity, such as polyethylene or polypropylene, have been formed on the inside surfaces of the side walls 24 and 26 to decrease the sliding resistance between the side walls 24 and 26 and seal lips 20 and 22. This arrangement, however, cannot prevent such noises completely.
The present inventors have found that these noises do not occur when the seal lips rub the inside surfaces of the side walls of the glass run, but occur when the seal lips of rubber, which have been in close contact with the inside surfaces of the side walls of rubber, separate therefrom. Based on this finding, they have studied and succeeded in preventing occurrence of these noises by forming linear ridges in parallel with each other on the inside surfaces of the side walls in the longitudinal direction of the main body such that the seal lips come into approximately linear contact with the linear ridges, thereby reducing the contacting area of the seal lips with the side walls (Japanese patent application No. Hei 11-313771).
The present inventors have further conducted many experiments, and found that the reason for noises occurring in the glass run provided with such films of high lubricity is the hardness of such films. The hardness of the films of high lubricity is much greater than that of the glass run. Consequently, the seal lips which have been in close contact with such films instantly separate therefrom without any occurrence of noises. However, noises occur when the seal lips strike on these hard films.
It is an object of the present invention to provide a glass run capable of preventing occurrence of noises when a vehicle door is closed hard or a vehicle runs on rough roads with a door glass half opened.
More specifically, it is an object of the present invention to provide a glass run capable of preventing occurrence of such noises without modifying surfaces of a main body thereof, which are to contact seal lips, into a specific configuration, or without providing films composed of materials different from those of the main body on surfaces of the main body, which are to contact seal lips.
The glass run of the present invention is fitted inside a doorframe of a motor vehicle. The glass run of the present invention has a main body with a generally U-shaped cross section, and a pair of seal lips which extend obliquely inwardly from ends of side walls of the main body for holding the periphery of a door glass. At least the main body contains a fine powder of lubricant in a dispersed condition. At least one of silicon powder, polyamide resin powder, molybdenum disulfide powder and fatty acid amide powder is used as the lubricant. The preferred content of the lubricant ranges from 0.2 to 1.0% by weight of the material composing parts of the glass run, in which the lubricant is contained.
The hardness of the main body scarcely increases with the dispersion of fine lubricant powder, and the inside surfaces of the main body exhibit rubber-like elasticity, thereby preventing occurrence of noises when the seal lips strike on the main body. In addition, by virtue of the lubricant dispersed in the inside surfaces of the main body, separation of seal lips therefrom is facilitated without any occurrence of noises.
Alternatively, foamed layers composed of a material identical to that of the main body of the glass run may be formed on the inside surfaces of the main body, which face the seal lips. The foamed layers exhibit rubber-like elasticity, and the surfaces thereof have minute irregularities, and consequently, the contacting area of the seal lips with the surfaces of the foamed layers is small. This results in noises upon striking and separating of the seal lips on and from the main body being prevented.
Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification.